The sole survivor of an ancient lineage, the New Zealand lesser short-tailed bat is believed to be one of only two native terrestrial mammals in New Zealand. Its only close relative, the greater short-tailed bat (Mystacina robusta), was last sighted in the 1960s and is believed to be extinct. Unlike most bats which catch their prey in the air, the short-tailed bat has adapted to hunting on the ground. It is regarded as the world’s most terrestrial bat, and has evolved to fill the niche of mice or shrews in other parts of the world. The terrestrial behaviour of the species makes it particularly vulnerable to predation by rats and feral cats, which were introduced to New Zealand by Europeans.

Urgent Conservation Actions

Habitat protection, monitoring programmes throughout the species' range and further research into ecology, habitat uses and threats so that effective management practices can be implemented.

Bats are New Zealand's only endemic land mammals. In proverb, the Maori refer to bats as pekapeka and associate them with the mythical, night-flying bird, hokioi, which foretells death or disaster.

Evolutionary Distinctiveness

Order: Chiroptera

Family: Mystacinidae

Recent molecular analyses place this species in the superfamily Noctilionoidea (formerly Phyllostomoidea). This superfamily is thought to have evolved in Gondwana and exhibits a greater diversity than any other bat superfamily. It is divided into four families: Mystacinidae (2 species), Noctilionidae or fishing bats (2 species), Mormoopidae or moustached bats (8 species), and the Phyllostomidae or New World leaf-nosed bats (147 species).

The Mystacinidae is believed to be the most basal group in the superfamily, and is the only family not restricted to Central or South America. Until recently, the lesser short-tailed bat (M. tuberculata) was believed to be the sole survivor of this ancient family. Its closest relative, the greater short-tailed bat (M. robusta), was last sighted in the 1960s and is believed to be possibly extinct.

New Zealand has an extremely poor ancient fossil record and the oldest known fossil remains of Mystacina are probably less than 20,000 years old. However, the genus is considered to be an endemic archaic element of New Zealand's fauna, having no close relatives elsewhere in the world. Estimations for the separation of Mystacina’s ancestors from other noctilionoids vary from 68-35 million years ago. The only ancient mystacinid fossils known are from the early-mid Miocene of Australia, and it is believed that the superfamily evolved and became widespread in the ancient southern supercontinent of Gondwana after New Zealand’s separation around 80 million years ago. The family is thought to have dispersed from Australia to New Zealand sometime after the Oligocene (26 million years ago).

Regarded as the world’s most terrestrial bat, the lesser short-tailed bat is almost as much at home on the ground as it is in the air. It has a number of adaptations to its unique lifestyle. When not flying, it can fold its wings under a leathery membrane that runs along the side of its body, forearms and lower legs. This enables the bat to use its forearms like front legs for walking or climbing on the ground. The short tail is free of the wing membrane. The bat’s thumb has a large claw with a small talon projecting from it, a unique feature among the smaller bats. The feet also have talons, which enable to bats to move with agility on the ground and even climb trees. The bat’s fur is short and velvety, and thicker than that of most bats. The fur is greyish brown on the upper surface and paler below. The bat is rather stocky, with disproportionately large ears and a short muzzle with vertically aligned nostrils.

Ecology

Until the arrival of humans, New Zealand had no native mammals other than bats. Having evolved in the absence of terrestrial predators this little bat became adept on the ground, filling the niche occupied by rodents or shrews in other parts of the world. The bat’s ability to fold its wings away enables it to forage amongst litter and humus on the forest floor without damaging its delicate flight membranes. The species feeds primarily on terrestrial invertebrates, although fruit, nectar and pollen are also eaten. It is thought to be an important pollinator of a number of plants, including woodrose (Dactylanthus), a threatened parasitic plant which grows on the roots of trees on the forest floor. The bat locates its food through a combination of echolocation, smell and sound. The species is nocturnal, roosting in small groups in hollow trees. It is thought that individuals use their teeth and claws to burrow into the rotten wood to excavate cavities for roosting.

During cold weather the bats are thought to go into a state of torpor to conserve energy. Their body temperatures and metabolic rates drop, and they can remain inactive for several days without emerging from their roosts. During the breeding season, males are thought to compete for females via a lek mating system where males compete for the best position in which to ‘sing’ to attract a female. Mating occurs in the autumn (February to May) and the females give birth to a single young the following summer (December to January).

Habitat

Generally found in old-growth indigenous forests which contain large trees suitable for colonial roosts. The species is sometimes reported from logged forest, scrubland, pine plantations and farmland in areas close to areas of undamaged old-growth forest.

Distribution

Endemic to New Zealand. The species is found in several areas in the North Island and at least two areas in the South Island. It is also found on Little Barrier Island and several smaller islands off Stewart Island.
The northern, or kauri forest short-tailed bat, is found only at two sites in Northland and one on Little Barrier Island. The volcanic plateau short-tailed bat is known from Northland, the central North Island and Taranaki. The southern subspecies is restricted to Codfish Island and the northwest Nelson and Fiordland areas of the South Island.

The main threats are habitat loss, and predation and competition with introduced animals. The bats are thought to have declined as a result of forest clearance following human settlement of New Zealand. Although forest clearance is now limited, some selective logging continues, and this targets the larger, older trees that provide favoured roost sites. The terrestrial behaviour of the species makes it particularly vulnerable to predation by rats and feral cats, which were introduced to New Zealand by Europeans. The bats may also be vulnerable to poisoning from ground-laid poison baits set to kill introduced pests.

Conservation Underway

The species is fully protected within New Zealand. The Department of Conservation (New Zealand) has listed the lesser short-tailed bat as a high priority species for conservation attention. It has produced a Bat Recovery Plan in 1995 which aims to conserve all bat subspecies throughout their present range and to establish new populations where possible. New survey and research techniques are being developed that will enable researchers to identify important colonies and behavioural and habitat requirements. Most conservation action to date has concentrated on the few known larger roosts. In February 2005 20 pups from the unique and isolated Waiohine colony were transferred to Kapiti Island to establish a second safe population in a predator-free environment. If the transfer proves successful, more young bats will be brought to the island over the next 4-5 years.

Conservation Proposed

The Bat Recovery Plan and the 2001 IUCN/SSC Microchiropteran Bats Action Plan recommend that important habitats are protected and the bats are monitored throughout their range. Further research into the ecology, habitat uses and threats facing mainland populations is needed in order to implement effective management practices. If the establishment of a new colony on Kapiti Island proves successful then colonies of other subspecies should be established on suitable rat-free islands within their known ranges. It is important to raise public awareness of the species and involve the public in bat conservation.